Controlled Synthesis of Nitrogen-Doped Yolk–Shell Carbon Nanospheres: Tailoring Yolk Size for Lithium–Sulfur Batteries

Nitrogen-doped yolk–shell carbon nanoparticles are one of the most promising functional nanomaterials for various potential applications because of their functionality and adaptability in both the hollow shells and yolks. Yolk–shell nanospheres are known for widely adopted template-based routes, which prove to be expensive and cumbersome and showed inadequate capability to build complex internal structures. Herein, a facile and controllable strategy for fabricating nitrogen-doped yolk–shell carbon nanospheres was proposed through a simple leaching process. The production of the yolk–shell structure is based on the selective dissolution of inhomogeneous solid polymer nanospheres using methanol as leaching agent. The yolk sizes of the nanospheres can be controlled in the range 110–360 nm by simply varying the number of leaching times. In particular, results of the electrochemical properties of the prepared nanospheres with different yolk size suggest that the optimal yolk–shell nanospheres with a yolk size of ∼230 nm delivered the best cycling performance and good capacity retention of 582 mAh g–1 at 1 C after 200 cycles. We believe that the proposed strategy will play a crucial role in energy storage application.